1. Field of the Invention;
The present invention relates to an improvement in continuous development of photographed films or microfilms. It relates also to an improvement in continuous development of photographed films or microfilms and successive printing of images through the developed films.
2. Prior Art Statement
When plural roll films or microfilms are continuously developed, it becomes necessary to control the density of developed images to a proper level. The density of developed images becomes too low as the developing liquid is fatigued or the film feed rate is too high. The density of developed images becomes too low when the concentration of developing reagent in the developing liquid is low, the liquid level in the developing liquid vessel is low or the temperature of the developing liquid is low. For the variation in these parameters in the developing step, it becomes difficult to control the density of the developed images to an appropriate density even if the film is exposed to a proper quantity of light at the photographing step by the use of an automatic exposure control device.
In order to control the developing operation so that the developed images have proper densities, it has been proposed to monitor the densities of the images simultaneously during the developing operation and to stop development when the density of developed image reaches a proper level. For example, Unexamined Japanese Patent Publication No. 181042/1983 (corresponding to Unexamined German Patent Publication DE-OS 3211946A) discloses a process for developemnt of an aperture card which has a microfilm strip mounted in an aperture grid of boards. The aperture card is maintained in the standstill condition and a developing liquid is sprayed onto the microfilm strip while the density of the developed images to monitored, and spraying of the developing liquid is stopped when the density of the developed images reaches a proper level, followed by immediate sparying of a fixing liquid to stop the developing operation. However, in this known process, the average density of the developed whole image is detected. Accordingly, some images have improper density levels depending on the contents of individual images.
When the densities of developed images in long films are controlled by varying the film feed rate, there arises a problem that the film feed rates at the subsequent fixing and rinsing steps are varied inevitably. Without changing the film feed rate, densities of developed images may be controlled by varying the concentration of developing reagent in the developing liquid. Otherwise, densities of developed images may be controlled by controlling the quantity of developing liquid contacting with the film or by varying the temperature of the developing liquid. However, high responsiveness is not expected in such a control system.
In reproduction of a microfilm or in printing of images of a film, it is required to control the condition of printing operation in response to the densities of developed images. In the conventional technology, the light quantity in the printing operation is determined by detecting the density of the developed image area. However, proper exposure light quantity cannot be monistically set, since the detected density is varied as the monitored image area is changed.